/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    RemoveFolds.java
 *    Copyright (C) 1999-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.filters.unsupervised.instance;

import java.util.Enumeration;
import java.util.Random;
import java.util.Vector;

import weka.core.Capabilities;
import weka.core.Capabilities.Capability;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.Utils;
import weka.core.WeightedAttributesHandler;
import weka.filters.Filter;
import weka.filters.UnsupervisedFilter;

/**
 * <!-- globalinfo-start --> This filter takes a dataset and outputs a specified
 * fold for cross validation. If you want the folds to be stratified use the
 * supervised version.
 * <p/>
 * <!-- globalinfo-end -->
 * 
 * <!-- options-start --> Valid options are:
 * <p/>
 * 
 * <pre>
 * -V
 *  Specifies if inverse of selection is to be output.
 * </pre>
 * 
 * <pre>
 * -N &lt;number of folds&gt;
 *  Specifies number of folds dataset is split into. 
 *  (default 10)
 * </pre>
 * 
 * <pre>
 * -F &lt;fold&gt;
 *  Specifies which fold is selected. (default 1)
 * </pre>
 * 
 * <pre>
 * -S &lt;seed&gt;
 *  Specifies random number seed. (default 0, no randomizing)
 * </pre>
 * 
 * <!-- options-end -->
 * 
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision$
 */
public class RemoveFolds extends Filter implements UnsupervisedFilter, OptionHandler, WeightedAttributesHandler {

    /** for serialization */
    static final long serialVersionUID = 8220373305559055700L;

    /** Indicates if inverse of selection is to be output. */
    private boolean m_Inverse = false;

    /** Number of folds to split dataset into */
    private int m_NumFolds = 10;

    /** Fold to output */
    private int m_Fold = 1;

    /** Random number seed. */
    private long m_Seed = 0;

    /**
     * Gets an enumeration describing the available options..
     * 
     * @return an enumeration of all the available options.
     */
    @Override
    public Enumeration<Option> listOptions() {

        Vector<Option> newVector = new Vector<Option>(4);

        newVector.addElement(new Option("\tSpecifies if inverse of selection is to be output.\n", "V", 0, "-V"));

        newVector.addElement(new Option("\tSpecifies number of folds dataset is split into. \n" + "\t(default 10)\n", "N", 1, "-N <number of folds>"));

        newVector.addElement(new Option("\tSpecifies which fold is selected. (default 1)\n", "F", 1, "-F <fold>"));

        newVector.addElement(new Option("\tSpecifies random number seed. (default 0, no randomizing)\n", "S", 1, "-S <seed>"));

        return newVector.elements();
    }

    /**
     * Parses a given list of options.
     * <p/>
     * 
     * <!-- options-start --> Valid options are:
     * <p/>
     * 
     * <pre>
     * -V
     *  Specifies if inverse of selection is to be output.
     * </pre>
     * 
     * <pre>
     * -N &lt;number of folds&gt;
     *  Specifies number of folds dataset is split into. 
     *  (default 10)
     * </pre>
     * 
     * <pre>
     * -F &lt;fold&gt;
     *  Specifies which fold is selected. (default 1)
     * </pre>
     * 
     * <pre>
     * -S &lt;seed&gt;
     *  Specifies random number seed. (default 0, no randomizing)
     * </pre>
     * 
     * <!-- options-end -->
     * 
     * @param options the list of options as an array of strings
     * @throws Exception if an option is not supported
     */
    @Override
    public void setOptions(String[] options) throws Exception {

        setInvertSelection(Utils.getFlag('V', options));
        String numFolds = Utils.getOption('N', options);
        if (numFolds.length() != 0) {
            setNumFolds(Integer.parseInt(numFolds));
        } else {
            setNumFolds(10);
        }
        String fold = Utils.getOption('F', options);
        if (fold.length() != 0) {
            setFold(Integer.parseInt(fold));
        } else {
            setFold(1);
        }
        String seed = Utils.getOption('S', options);
        if (seed.length() != 0) {
            setSeed(Integer.parseInt(seed));
        } else {
            setSeed(0);
        }
        if (getInputFormat() != null) {
            setInputFormat(getInputFormat());
        }

        Utils.checkForRemainingOptions(options);
    }

    /**
     * Gets the current settings of the filter.
     * 
     * @return an array of strings suitable for passing to setOptions
     */
    @Override
    public String[] getOptions() {

        Vector<String> options = new Vector<String>();

        options.add("-S");
        options.add("" + getSeed());
        if (getInvertSelection()) {
            options.add("-V");
        }
        options.add("-N");
        options.add("" + getNumFolds());
        options.add("-F");
        options.add("" + getFold());

        return options.toArray(new String[0]);
    }

    /**
     * Returns a string describing this filter
     * 
     * @return a description of the filter suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String globalInfo() {
        return "This filter takes a dataset and outputs a specified fold for " + "cross validation. If you want the folds to be stratified use the " + "supervised version.";
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String invertSelectionTipText() {

        return "Whether to invert the selection.";
    }

    /**
     * Gets if selection is to be inverted.
     * 
     * @return true if the selection is to be inverted
     */
    public boolean getInvertSelection() {

        return m_Inverse;
    }

    /**
     * Sets if selection is to be inverted.
     * 
     * @param inverse true if inversion is to be performed
     */
    public void setInvertSelection(boolean inverse) {

        m_Inverse = inverse;
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String numFoldsTipText() {

        return "The number of folds to split the dataset into.";
    }

    /**
     * Gets the number of folds in which dataset is to be split into.
     * 
     * @return the number of folds the dataset is to be split into.
     */
    public int getNumFolds() {

        return m_NumFolds;
    }

    /**
     * Sets the number of folds the dataset is split into. If the number of folds is
     * zero, it won't split it into folds.
     * 
     * @param numFolds number of folds dataset is to be split into
     * @throws IllegalArgumentException if number of folds is negative
     */
    public void setNumFolds(int numFolds) {

        if (numFolds < 0) {
            throw new IllegalArgumentException("Number of folds has to be positive or zero.");
        }
        m_NumFolds = numFolds;
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String foldTipText() {

        return "The fold which is selected.";
    }

    /**
     * Gets the fold which is selected.
     * 
     * @return the fold which is selected
     */
    public int getFold() {

        return m_Fold;
    }

    /**
     * Selects a fold.
     * 
     * @param fold the fold to be selected.
     * @throws IllegalArgumentException if fold's index is smaller than 1
     */
    public void setFold(int fold) {

        if (fold < 1) {
            throw new IllegalArgumentException("Fold's index has to be greater than 0.");
        }
        m_Fold = fold;
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String seedTipText() {

        return "the random number seed for shuffling the dataset. If seed is negative, shuffling will not be performed.";
    }

    /**
     * Gets the random number seed used for shuffling the dataset.
     * 
     * @return the random number seed
     */
    public long getSeed() {

        return m_Seed;
    }

    /**
     * Sets the random number seed for shuffling the dataset. If seed is negative,
     * shuffling won't be performed.
     * 
     * @param seed the random number seed
     */
    public void setSeed(long seed) {

        m_Seed = seed;
    }

    /**
     * Returns the Capabilities of this filter.
     * 
     * @return the capabilities of this object
     * @see Capabilities
     */
    @Override
    public Capabilities getCapabilities() {
        Capabilities result = super.getCapabilities();
        result.disableAll();

        // attributes
        result.enableAllAttributes();
        result.enable(Capability.MISSING_VALUES);

        // class
        result.enableAllClasses();
        result.enable(Capability.MISSING_CLASS_VALUES);
        result.enable(Capability.NO_CLASS);

        return result;
    }

    /**
     * Sets the format of the input instances.
     * 
     * @param instanceInfo an Instances object containing the input instance
     *                     structure (any instances contained in the object are
     *                     ignored - only the structure is required).
     * @return true because outputFormat can be collected immediately
     * @throws Exception if the input format can't be set successfully
     */
    @Override
    public boolean setInputFormat(Instances instanceInfo) throws Exception {

        if ((m_NumFolds > 0) && (m_NumFolds < m_Fold)) {
            throw new IllegalArgumentException("Fold has to be smaller or equal to " + "number of folds.");
        }
        super.setInputFormat(instanceInfo);
        setOutputFormat(instanceInfo);
        return true;
    }

    /**
     * Input an instance for filtering. Filter requires all training instances be
     * read before producing output.
     * 
     * @param instance the input instance
     * @return true if the filtered instance may now be collected with output().
     * @throws IllegalStateException if no input structure has been defined
     */
    @Override
    public boolean input(Instance instance) {

        if (getInputFormat() == null) {
            throw new IllegalStateException("No input instance format defined");
        }
        if (m_NewBatch) {
            resetQueue();
            m_NewBatch = false;
        }
        if (isFirstBatchDone()) {
            push(instance);
            return true;
        } else {
            bufferInput(instance);
            return false;
        }
    }

    /**
     * Signify that this batch of input to the filter is finished. Output() may now
     * be called to retrieve the filtered instances.
     * 
     * @return true if there are instances pending output
     * @throws IllegalStateException if no input structure has been defined
     */
    @Override
    public boolean batchFinished() {

        if (getInputFormat() == null) {
            throw new IllegalStateException("No input instance format defined");
        }

        Instances instances;

        if (!isFirstBatchDone()) {
            if (m_Seed > 0) {
                // User has provided a random number seed.
                getInputFormat().randomize(new Random(m_Seed));
            }
            // Push instances for output into output queue

            // Select out a fold
            if (!m_Inverse) {
                instances = getInputFormat().testCV(m_NumFolds, m_Fold - 1);
            } else {
                instances = getInputFormat().trainCV(m_NumFolds, m_Fold - 1);
            }
        } else {
            instances = getInputFormat();
        }

        flushInput();

        for (int i = 0; i < instances.numInstances(); i++) {
            push(instances.instance(i), false); // No need to copy instance because of bufferInput()
        }

        m_NewBatch = true;
        m_FirstBatchDone = true;
        return (numPendingOutput() != 0);
    }

    /**
     * Main method for testing this class.
     * 
     * @param argv should contain arguments to the filter: use -h for help
     */
    public static void main(String[] argv) {
        runFilter(new RemoveFolds(), argv);
    }
}
